Problem with Tone Bender Mk II (Aion Deimos PCB)

[guitargeek]

Hey all,

So, I've built 7 pedals - 1 from perfboard, 6 from PCBs, and this TBMkII is the first time I've run into an issue that I couldn't quickly resolve.

The problem is that the pedal goes into uncontrollable feedback with the fuzz turned up past about 9:00. Also, when I roll the guitar volume down I start hearing radio interference when the vol pot hits 0. A final oddity, it doesn't seem to be fully bypassed when the pedal is switched off. I can hear slight variances in the guitar signal when the pedal is bypassed as I manipulate the volume and fuzz knobs on the pedal.

I've looked over all the wiring and all the solder joins. I had tested all the resistors before assembly. The transistors are all getting power and are properly biased.

One thing I didn't check was the caps. Does this sound like a potential cap issue?

Any ideas what my problem might be? I'm hoping this all sounds symptomatic of a specific problem, but as my experience is limited I'm at a loss.

[Electric Warrior]

The size of the power filter cap can critical, but I see the schematic you used specifies a 50µF, so it should be good.

Are you using a battery for power supply?

[guitargeek]

No, 9v power supply.

Sent from my SM-G930W8 using Tapatalk

[Electric Warrior]

Maybe try a battery then to see if it fixes the issue.

[GibsonGM]

Welcome to the forum...is the pedal inside an enclosure right now, or is it assembled but with the wiring all exposed?

If in the enclosure, ok, there is a problem.   If outside the enclosure, I'd suggest 100th-double checking your switch and jack wiring, and maybe using a shielded wire for the input lead.   It's almost always a wiring error...